I recently jumped into Vshere to perform the simple task of extending the size of one of the hard disks. I found that the possibility to extend the virtual hard disk was greyed out.
I checked with a couple of other systems and it was possible on all of them. What would be the difference between this particular VM and the others?
After some time investigating, the reason was finally found and it was actually easy in the end. There was a snapshot on this VM! Which I had found that there had been a backup job running for a few days and was locked up and had not been checked.
Unfortunately in the new web-based vSphere user interface, an active snapshot cannot be seen as fast as in the earlier vSphere days (VMware Infrastructure and vSphere GUI). To check if a virtual machine still holds a snapshot, the “Actions” drop down menu needs to be opened, followed by the “Snapshots” entry to then finally click on “Manage Snapshots”.
And here, finally, the snapshot can be deleted:
Once the backup had completed or snapshot was deleted, the virtual hard disks could be (online) resized again: